Parallax-free indicator devices, systems, and methods

A device, comprising:

• a housing defining an aperture;
• a fastener, wherein the housing is selectively securable via the fastener to an instrument in a selected orientation relative to the instrument;
• and
• a light source assembly at least partially disposed in the housing, the light source assembly comprising:
• a light source operably coupled to a power source via a power circuit, wherein the light source comprises a laser or a light-emitting diode and is positioned within the housing to emit light through the aperture of the housing, wherein, upon activation, the light source assembly emits a parallax-free alignment indicator along an alignment axis having at least one of a selected angle or a selected displacement relative to a selected reference axis, wherein the alignment indicator is configured to be rotatable about at least three alignment axes to adjust a roll, a pitch, and a yaw of the alignment indicator, and wherein the alignment indicator is configured to guide a surgical procedure;
• and
• an adjuster for selectively adjusting at least one of the selected angle or the selected displacement of the alignment indicator;
• wherein the adjuster comprises at least one of a mirror or a lens;
• wherein the alignment axis is adjustable in fixed increments about and between a first angle and a second angle with respect to the selected reference axis;
• wherein the power circuit comprises a first lead and a second lead, both exposed on an exterior surface of the housing in a location designed to contact a metal object to complete the power circuit and activate the light source;
• and
• wherein the metal object comprises a portion of the fastener.